While studying the role the basal ganglia pathway in learned vocal communication, we discovered an unexpected phenomenon: following neurotoxic lesions, the avian striatum recovered itself. This phenomenon, as far as we know, is unprecedented in the mammalian brain. Here we propose to investigate the mechanisms of this recovery: whether this is in fact new neuron regeneration or neuron invasion from the surrounding areas. Further we will determine the time course of this recovery accompanied with the behavioral (song) recovery. We will identify whether the cellular organization in the recovered striatum is the same as in intact striatum. Finally, we will test whether the recovery is specific to the neurotoxic lesion or if it is a more general aspect of the avian striatum. As the avian striatum contains neurons similar in their electrophysiological and molecular properties to their mammalian counterparts, the project is expected to impact our understanding of brain regeneration. The relevance of this research to public health is that we would find potential ways to repair damaged basal ganglia brain areas, and in particular for correcting speech deficits. This research will be done primarily in Slovakia at the Institute of Animal Biochemistry and Genetics at the Slovak Academy of Sciences in collaboration with Lubica Kubikova, as an extension of NIH grant #R01 DC007218-01. [unreadable] [unreadable] [unreadable]